Excitation energy dependence of electron-phonon interaction in ZnO nanoparticles

TL;DR

This study investigates how excitation energy influences electron-phonon interactions in ZnO nanoparticles using Raman spectroscopy, revealing significant Frohlich interaction contributions near resonance and comparing mechanisms with bulk ZnO.

Contribution

First estimation of the relative strength of Frohlich and deformation potential mechanisms in ZnO nanoparticles compared to bulk material.

Findings

Frohlich interaction dominates near resonance energies.

Intensities of Raman modes vary significantly with excitation energy.

Comparison shows different electron-phonon coupling in nanoparticles versus bulk.

Abstract

Raman spectroscopic investigations are carried out on ZnO nanoparticles for various photon energies. Intensities of E1-LO and E2 modes exhibit large changes as the excitation energy varied from 2.41 to 3.815 eV, signifying substantially large contribution of Frohlich interaction to the Raman polarizability as compared to deformation potential close to the resonance. Relative strength of these two mechanisms is estimated for the first time in nanoparticles and compared with those in the bulk.